It is well known to provide a motor vehicle occupant restraint system having a shoulder belt which extends over the shoulder and across the chest of the seated occupant. An inertia responsive seat belt retractor is conventionally associated with one end of the shoulder belt and has a windup spring which rotates a reel to wind or retract the belt to a taut condition across the chest of the occupant. The inertia retractor permits belt unwinding rotation of the reel to extend the belt as the occupant leans forwardly to reach the vehicle operating controls and locks the belt against extension in response to an acceleration stimulus experienced by the vehicle body.
It is also known to provide a retractor having a winding prevention mechanism which enhances occupant comfort locking the reel against belt winding rotation by the windup spring to hold the belt at a set length establishing a slackened condition about the occupant. U.S. Pat. No. 4,023,746, issued to Joseph J. Magyar on May 17, 1977, provides an inertia locking retractor having a winding prevention mechanism which is selectively actuated and deactuated in response to a predetermined sequence of reel rotation induced by movement of the restrained occupant.
U.S. Pat. No. 3,700,184, issued to R. E. Francis on Oct. 24, 1972 and U.S. Pat. No. 3,682,412, issued to G. G. Kuszynski on Aug. 8, 1972 provide inertia locking retractors having winding prevention mechanisms which are manually actuated and deactuated without regard to the condition or sequence of belt winding retraction or unwinding extension.
U.S. Pat. No. 3,973,786, issued to L. W. Rogers, Jr. on Aug. 10, 1976, discloses a winding prevention mechanism of the Magyar type which is interconnected with the door for deactuation whenever the door is in the open position to insure belt winding rotation.
It is also known to provide a passive belt system having one end of the belt mounted on the door, another end of the belt mounted on the vehicle body inboard the seat, and a retractor associated with one of the belt ends for winding the belt to a taut position about the occupant upon closing movement of the door and unwinding the belt to a stowed position forwardly of the seat upon opening movement of the door.
It would be desirable to employ a winding prevention retractor in a door responsive passive seat belt system to enhance occupant comfort. However, it has been found that the Magyar type winding prevention mechanism which is controlled in response to the predetermined sequence of belt winding and unwinding could be subject to unintended actuation of the winding prevention mechanism upon inadvertent random oscillatory movement of the door in the open position so that the belt would not be wound to the restraining position about the occupant upon closure of the door. The Francis or Kuszynski type retractor could be used in a door responsive passive belt system but it would be necessary for the occupant to manually set the winding prevention mechanism subsequent to movement of the belt to the restraining position by closure of the door and to also manually release the winding prevention mechanism. If the occupant did not manually release the winding prevention mechanism before opening the door or before a subsequent closure of the door, the retractor would reestablish the previously set belt length irrespective of a different occupant entering the seat or the seat position being adjusted. Accordingly, an excessive amount of slack could result. The Rogers type retractor having the winding prevention mechanism interconnected with the door could be used in a door responsive passive belt system but a remote interconnect would be required in those instances where it is desired to mount the retractor inboard the occupant seating position. Furthermore, the use of a Rogers type door interconnect would render the winding prevention mechanism immediately operative in response to belt unwinding subsequent to closure of the door, even in those instances where the occupant may not have assumed his final adjusted position in the seat prior to closing movement of the door or where the occupant may not require or desire the use of this comfort enhancing feature.
The present invention features a new and improved winding prevention mechanism which is manually actuated subsequent to winding of the belt to the restraining position by closure of the door and is automatically released in response to reel rotation upon unwinding of the belt during opening movement of the door to assure winding of the belt and complete movement to a taut restraining position upon subsequent closure of the door.